/*
 * Copyright 2012-2022 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.autoconfigure.batch;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.boot.autoconfigure.batch.BatchProperties.Isolation;
import org.springframework.boot.autoconfigure.transaction.TransactionManagerCustomizers;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;

/**
 * 针对 JPA 定制的 {@link BasicBatchConfigurer} 实现。
 *
 * @author Stephane Nicoll
 * @since 2.0.0
 */
public class JpaBatchConfigurer extends BasicBatchConfigurer {

	private static final Log logger = LogFactory.getLog(JpaBatchConfigurer.class);

	private final EntityManagerFactory entityManagerFactory;

	/**
	 * 创建一个新的 {@link BasicBatchConfigurer} 实例。
	 * @param properties 批处理相关配置属性
	 * @param dataSource 底层数据源
	 * @param transactionManagerCustomizers 事务管理器定制器（可为 {@code null}）
	 * @param entityManagerFactory 实体管理工厂（可为 {@code null}）
	 */
	protected JpaBatchConfigurer(BatchProperties properties, DataSource dataSource,
			TransactionManagerCustomizers transactionManagerCustomizers, EntityManagerFactory entityManagerFactory) {
		super(properties, dataSource, transactionManagerCustomizers);
		this.entityManagerFactory = entityManagerFactory;
	}

	@Override
	protected String determineIsolationLevel() {
		String name = super.determineIsolationLevel();
		if (name != null) {
			return name;
		}
		else {
			logger.warn("JPA does not support custom isolation levels, so locks may not be taken when launching Jobs. "
					+ "To silence this warning, set 'spring.batch.jdbc.isolation-level-for-create' to 'default'.");
			return Isolation.DEFAULT.toIsolationName();
		}
	}

	@Override
	protected PlatformTransactionManager createTransactionManager() {
		return new JpaTransactionManager(this.entityManagerFactory);
	}

}
